made your decision (now you're gonna have a bad time)
by DeanGirl2Y5
Summary: (contains spoilers for Undertale's Genocide Route.) (*ACT: FIGHT) kill or be killed, the only thing that matters who's the m o n s t e r now? the human shows no mercy, why should you?


**WARNING: THIS FIC CONTAINS SPOILERS FOR THE GENOCIDE ROUTE (AND SOME PLOT POINTS) OF THE GAME UNDERTALE, ALONG WITH IMPLIED MAJOR/MAIN CHARACTER DEATH. IF YOU HAVEN'T PLAYED/WATCHED SOMEONE PLAY UNDERTALE, DO IT NOW! please and thank you! :)  
**

 _ **A/N: Title is from "Ashes" by NateWantsToBattle. 90% of the dialogue comes directly from the game.**_

 _ **My first Undertale fic! I know I should be working on "Sun Rise," but I really got into Undertale recently, so I created another OC just for the game, named Sonia Babiole (yes, her last name is a font. I know Sans, Papyrus, and Gaster are the only characters named after fonts, but I thought the concept was pretty cool. I pretty much used a random name generator to come up with her first name). If any of the canon characters are OOC to you, feel free to let me know.  
**_

 _ **Constructive comments are welcome as this is my first Undertale fic. As mentioned in the additional tags, I switch POVs between Sans and my OC Sonia.**_

 _ **Ex.**_ (sans's pov is like this, in all lowercase just like in the game. **[** _his flashbacks are like this._ **].** _his thoughts are like this._ ) Sonia's POV looks like this. _ **(** Her thoughts and flashbacks look like this. **)**_ "Here's Sonia's dialogue." "here's sans's dialogue." "HERE'S THE GREAT PAPYRUS'S DIALOGUE!"

 _ **I'm also working with my personal headcanon (I blame all the Undertale SFMs I've been watching, mostly with "Stronger than You," where I've seen Chara wearing Papyrus's scarf.) that Chara carries items belonging to the boss monsters they've killed, like serial killers. I'm using they/them pronouns for both Frisk and Chara (and Sans occasionally calls Chara "the demon"), mostly since Frisk is the protagonist of the game. Also, I reference other path options from the game, so minor spoilers there. The only major spoilers are the ones concerning the Genocide path.**_

 _ **If anyone's curious, Sonia's half-human, half-cat monster, but the only parts of her that are human are her face, body, hair, and her blood. As for the monster part, she has cat fangs instead of normal human teeth, claws instead of nails, cat eyes instead of human eyes (her left eye is yellow, and her right eye is red. She covers her right eye with a cloth eyepatch, think Kaneki Ken's eyepatch from Tokyo Ghoul. For anyone who hasn't seen Tokyo Ghoul, google "kaneki ken's eyepatch."), her SOUL (yellow with cat whiskers), and black cat ears on top of her head. Sans's nickname for her is Sony, and Papyrus calls her Nia.  
**_

 _ **Let me know what you think!**_

 _ **DISCLAIMER: I own nothing but Sonia and her backstory. Undertale and all it's characters are owned by Toby Fox.**_

* * *

Sonia first heard about the human from a Froggit while she was leaving the shop in Snowdin.

It had come from the Ruins, yelling about a human that was killing every monster it saw.

And she ran all the way back there, worried for Toriel (mom was there, _MOM was there!)._

Past Greater and Lesser Dog.

Past Papyrus's puzzles.

Past Papyrus himself, ignoring his calls of her name.

Past one of Sans's illegal hot dog stands.

Even past Sans, who was standing by the poorly guarded bridge watching her. (she never noticed the sad look in his eye sockets, as if he'd watched her do this hundreds of times before.)

And made it to the door she'd exited from years earlier.

Half of her wanted to bang on the door and yell for Toriel, just to hear if she still lived. The other half wanted to break the door down and run back to the house and cling to Toriel to keep her safe.

( _Don't be dead, Mom. I can't lose you, too._ )

However, the door opened slightly before she could settle on what to do (which side to listen to) and she felt a familiar boney hand pull her behind the trees. Sonia turned around and saw Sans. She was about to ask why, but he pressed his pointer bones to his teeth, and she closed her mouth.

(sans mentally sighed in relief. four resets ago, sonia'd been dusted after confronting chara right after they left the ruins, and he'd had to watch that from the woods, his eyelights going out and his hands clenching in his pockets. chara probably realized in the judgement hall just how much that affected sans when they'd come in, sonia's blue rose hair bow clipped to the collar of their bloodied dust-covered shirt. it had pissed him off just as much as when he'd found papyrus's dust on the path to waterfall.

the blood was hers. they _both_ knew it. sonia's half-human, after all. no matter how much she denied it out of hate for the father that had said nothing when the other humans cried out _justice_ as they threw both her and her mother down to the underground.

[ _what do they know of justice?_ she'd asked him one night after a nightmare she'd had, practically spitting it out as if it were a curse word through her tears. ]

chara had been wearing her rose bow each time they fought. never in the same place, yet always visible. same with papyrus's scarf, a piece of toriel's dress, undyne's spear, mettaton's shoe.

as if she sensed what he was thinking about, she touched her hair bow with her claws. it was a subconscious act, but he clenched his hands into fists, knowing what was going to happen, what _could_ happen, he corrected.)

Sans's eyelights had gone out, and Sonia immediately grabbed one of his hands a second before the creaking door caught her attention.

And a human child walked out...

 _...and they were covered in dust._

But what caught Sonia's attention was the scrap of purple cloth sticking out of their front pocket. The cloth had a familiar pattern on it.

( _Mom's gone. Mom's dead. THEY KILLED MOM!_ )

And she growled low, wanting to go after the human ( _the real monster here_ ), but Sans held her back with his blue magic. She looked back at him, and the skeleton shook his head, his missing eyelights letting her know he'd seen the cloth too.

(sans could see tears in her uncovered yellow eye when she looked at him, and he knew her red eye was the same. he also knew what she saw, for it was one of the reasons for her death in previous genocide runs. her _main_ reason four resets ago. but he didn't want her to die. hell, he didn't want _anyone_ to die. but, as mentioned before, her death hurt him just as much as pap's. however, he was going to make sure she lived this time, even if he had to drag her to alphys's lab to do so.

he swore he'd never let chara kill sonia again.)

Sonia turned back to the ( _monstermonstermonster_ ) human, watching as they walked that same path to the bridge. They stepped over the branch.

Behind her, she heard Sans teleport and the branch break. Now, she was able to move as Sans's magic had dissipated. She went to make a move toward the path, but she was stopped by a blue wall. She was able to see through it, but she couldn't go ( _after the killer_ ) through. She knew _exactly_ who put up this magic wall, and she walked along the treeline with the child, watching ( _glaring at_ ) them.

(sans knew sonia was probably gonna be angry with him about putting up the wall the moment he teleported, but he wasn't going to let her die ever again. if he had to use his magic to protect her from chara, then so be it. his eyelights darted between her and chara. she was glaring at toriel's killer.

it wouldn't be the first time he protected her, and, if this route continued happening, it wouldn't be the last.

hopefully, chara wouldn't even notice her. after all, he'd practically _perfected_ that wall after the first time he pulled her back from the door and tested it with alphys. the royal scientist didn't question it and even let him know whether she could see the object or not. he'd even tried it with the amalgamates down in the true lab.

he broke the branch for the who knows what number time, and chara didn't even turn stop.

honestly, he thought the demon would grow bored of killing everything and everyone by this point, but they never did. they always had this twisted smirk on their face the moment they entered the judgement hall, their victims' former possessions hanging off them like trophies. sonia's blue rose bow was clearly their favorite.

he'd caught glimpses of chara before. once in a neutral route six resets earlier, when they'd spared everyone except for papyrus and sonia. and again in the next reset, where they'd only killed papyrus, and again where they'd only killed sonia. frisk reappeared and broke down all three times, crying and apologizing for it, signing with shaking hands that they didn't know why they'd done it. of course, sans had forgiven them without hesitation. yet, there were points, even during the next pacifist route, where chara glitched in for about ten seconds while sonia and frisk were joking around, the snowball frisk threw turned into a knife. he almost jumped in and shoved her out of the way to take the knife, but it shifted back into a snowball.

he could still see that terrified look that was on her face in that moment, especially at night.

he shook himself out of his thoughts as he came up to chara, who'd stopped inches away from the bridge. showtime.)

Sonia trusted Sans, but this was the first time he used this to block her movements.

Of course he'd used his magic to move her from his spot on the couch on different occasions when he was too lazy to pick her up. Or when he didn't feel like getting up to grab some ketchup from the kitchen or his joke book.

This...she'd never seen before in all the time she'd known him and Papyrus.

The human never looked her way, their eyes locked on Sans as he chuckled as the whoopee cushion went off the moment they shook his hand.

"heheh... the old whoopee cushion in the hand trick," he stated, with a grin. "it's ALWAYS funny."

The skeleton's grin seemed... _forced_ to her, moreso than usual. She'd even noticed when he left to work he looked even more tired than he usually is. She'd taken a mental note to take him to Grillby's and, maybe, talk about what was going on.

The human was silent, their hand dropping back to their side. Sonia, however giggled.

"that's, uh. your cue to laugh," Sans pointed out. "or, uh, to emote at all...?" He winked.

But the human still kept their silence, just staring him down. It was a kinda unsettling sight.

"gee, lady," she heard Sans mutter under his breath, "you really know how to pick 'em, huh...?"

(out of the corner of his eye sockets, sans saw sonia's fists clench and her exposed yellow eye land on chara's latest trophy. he'd glare at the demon, too, but he had a script to keep to.)

"OK, that's fine," Sans replied with a wink. "everyone's got their own sense of humor. i'm sans. sans the skeleton. im actually supposed to be on watch for humans right now. but... y'know... i dont really care about capturing anybody. now my brother, papyrus... he's a human-hunting FANATIC. hey, actually, i think that's him over there. i have an idea. go through this gate thingy. yeah, go right through. my bro made the bars too wide to stop anyone."

With that, the human and Sans (with Sonia behind him, protected by the wall that connected her to him like it was a leash) crossed the bridge, stopping in sight of a lamp that was conveniently shaped like the human and Sans's sentry post. While the human wasn't looking, Sonia saw Sans motion for her to stand at his post. Reluctantly, she did as he silently asked, watching the human as she did so while (just barely) avoiding the lamp. She sat down behind the post.

(once sonia was sitting at his post, sans stated, "quick, behind that conveniently-shaped lamp."

chara was silent and they didn't move.

"uh, ok, i guess you don't have to."

that was the moment when papyrus walked up.

"SANS! HAVE YOU FOUND THE HUMAN YET?!" he inquired.

"yeah," sans responded, winking.

That was when papyrus grew excited. "REALLY!? WOWIE! GUESS THAT'S SETTLED!" he turned around and was about to leave before he turned back around and asked, "BY THE WAY, HAVE YOU SEEN NIA?! SHE CAME RUNNING THIS WAY! SHE LOOKED VERY DISTRESSED!"

sans glanced over to his sentry post and saw the cat-girl in question peaking out, glaring at the demon. "i havent seen her, bro. but i'll definitely look for her."

pap only gave him a smile before he finally left.)

"that worked out, huh?" Sonia heard Sans ask as she stood up, refusing to look at the ( _monstermonstermonster_ ) human. There was something... _unsettling_ about them, and it wasn't just because of their dust-covered clothes or the fact that they were carrying a piece of Toriel's dress in their back pocket.

The... _thing..._ said nothing.

"...are you just gonna stare at me, or...?" Sans inquired.

The moment they started walking in the direction of Snowdin, Sans called, "well, i'll be straight-forward with you. my brother'd really like to see a human... so, y'know, it'd really help me out...," he paused, winking at their back, "if you kept pretending to be one."

With that, Sans walked away, Sonia following behind.

* * *

( _"say, i've been thinking. seems like you're gonna fight my brother pretty soon. here's some friendly advice. if you keep going the way you are now..." he closed his sockets, and, when he opened them again, his eyelights were out, "...you're gonna have a bad time."_ )

* * *

Sans and Sonia were chilling at the house. Sans was drinking ketchup and reading his joke book (she knew _exactly_ what was in that book, but she never told anyone). Sonia, on the other hand, was playing with her fingers, unsure of how to talk about what she wanted to talk about. The TV was off for once, as Papyrus was dealing with the human.

Sans had brought her back to the house the moment they left the ( _murderermurderermurderer_ ) human, much to her extreme displeasure. But he'd promised to tell her what happened with them versus Pap.

And it was just as unsettling as the human itself.

They just walked through Sans's and Pap's puzzles like it was no big deal. Sonia'd shuddered at Papyrus's retelling.

( _"I hate them," she'd told him when he'd finished._

" _...i know," Sans answered. "i do too." The second sentence was muttered under his breath, but she'd heard it anyway._

" _DON'T WORRY, NIA!" Papyrus reassured her. "I, THE GREAT PAPYRUS, AM GOING TO HAVE A TALK WITH THE HUMAN!"_ )

"...Sans?" she asked, catching the attention of the skeleton in question.

"sup, sony?" he answered, not looking up from his book.

"Is everything okay?"

"yeah, why'd you ask?" He'd responded too quickly, and they both knew it.

"I call baloney."

"dont you mean _below-knee?"_

She quickly stood up, her hands on her hips. "Sans the Skeleton, I'm being serious. I know you're more tired than usual, but you take naps and breaks more than I do. Hell, when we first saw that human, you practically freaked out. Your lights were out, and your hands were clenched. And you pulled me from the Ruins door when I just wanted to see if Toriel was okay. So, please, just tell me what's going on, Sans?"

Before he could even answer, he doubled over in pain, clenching his ribcage. His book fell to the floor, and Sonia quickly ran over.

(sans _knew_ what this pain meant. no matter how many times chara'd put him through this, it wouldn't hurt any less. sonia, sweet innocent sonia, checked him over, her earlier worry put on the back burner.

 _i'll protect you from that monster, sony. no matter what._ )

Sonia lifted up his shirt and saw that two of his ribs had cracked. She bolted to the kitchen, grabbed the kit with the bandages (she'd _insisted_ on it after Papyrus had come back one day from Undyne's with a burned patella), and gently wrapped Sans's ribs with the bandages.

"Tell me what's wrong, Sans." _I wanna fix it._

The punny skelebro sighed. "i'll explain later, OK?"

She smiled and nodded before looking outside. "Pap's taking a long time with the human, don't you think?" There was a note of worry in her voice.

Sans grinned. "dont worry. it's pap. he'll be fine. maybe they've just gone on a date or somethin'."

(his grin was fake, sans knew that. he was just glad that sonia hadn't caught it.)

Sonia stood up, chuckling. "I'm gonna go check on him anyway. For some reason, I've got this really bad feeling in my gut."

Sans stood up as well. "i'll go with ya."

"It's just outside of town, punny boy."

" _tibia_ honest, i'd rather come with you," ( _because your gut is more right than you think,_ he mentally added.) he replied with a wink, making her blush and giggle.

(sans liked sonia's giggles and laughs and chuckles. they were refreshing sounds to hear, especially when they were surrounded by death. for a while each genocide run, she almost made him believe she was oblivious to it.

 _almost._

but he saw her tears and hate-filled glares aimed at chara when she saw them wearing his brother's scarf, or holding a piece of toriel's dress or undyne's spear. he'd even seen her rip off her eyepatch to show her determined, hate-filled red and yellow gaze and bite and scratch at chara with everything she had...

...but it wasn't enough. it never was.

he let her lead him out the door and outside of town, hearing her swear that she was gonna kill papyrus for making her worry so much about him, even adding that no amount of spaghetti could—)

Sonia froze. There was no sign of the great Papyrus anywhere by the river. Everything seemed to be moving in slow motion as she let go of Sans's hand and yelled for Papyrus.

Tears were falling down her face like a waterfall as she called out his name.

" _PAPYRUS! PAP!"_

(the scene was all too familiar to sans. yet he still joined her in her frantic yelling for his brother. they split up to look for him, promising to make some sort of noise if they found him. he could hear her muttering, _"He'll be fine. He's okay. He's Papyrus, for crying out loud! He's the great Papyrus!"_ under her breath as she walked toward waterfall. he headed in the opposite direction, even though he knew exactly where pap's dust was.)

Sonia hugged herself tightly, peering through any bush that she saw.

"This better not be a freakin' joke, Papyrus!" she yelled, her voice cracking through her tears as she kept walking. "If it is, I won't eat anymore of your spaghetti!"

That was when she saw Papyrus's armorplate sticking out from the pile of snow. She almost sighed in relief.

"Thank Asgore I found you, Pap! I was gonna say that I'll eat at—"

The armor was empty, and his signature red scarf was missing. There was dust underneath his armor.

She fell to her knees in the snow and grabbed the armor, holding it to her chest as she screamed.

(the moment sans heard her scream, he immediately teleported over to her, fearing chara had already gotten to her.

instead, he came upon an all-too-familiar sight: sonia sitting like a froggit in the snow and rocking back and forth, clutching his brother's armor as if her life depended on it. he knelt down beside her and held her as she cried, tears falling from his eyesockets. he tried not to think about the first time he'd seen her reaction to finding pap's dust and empty armor.

that alone almost broke him. he hated seeing her cry, which gave him even more of a reason to hate chara. he couldn't even look at his brother's empty armor.)

Thirty minutes had passed, and Sonia stopped crying. She reached up and slowly pulled off her eyepatch, looking at Sans with her dual-colored eyes before wiping away the leftover tears.

"I hate them," she said. "I hate them, Sans. I wanna kill that dirty family killer."

"i do, too, sony," Sans responded without hesitation. "i do, too."

* * *

(sonia was safe. she was hidden in the true lab with the others. alphys confirmed it in her last phone call.

relief spread across him like a blanket. she wasn't gonna die this time. chara wasn't gonna find her and kill her.

now, however, sans was standing in the judgement hall, waiting for the demon himself to walk in.

and walk in they did.

just like the previous genocide runs, papyrus's scarf was around their neck, that piece of toriel's dress was in their front pocket, undyne's spear was on their back, mettaton's shoe was hanging on undyne's spear, and...

...his eyelights flickered out for a brief second at the last item, and chara smirked.

 _how had they gotten to her? she was safe. safesafesafe..._

...and sonia's blue rose hair bow was clipped in their hair. their shirt was covered in dust and blood.

 _sonia's blood._

"heya," he managed to say. "you've been busy, huh?"

as he expected, chara said nothing, instead clenching the knife tightly.

"so, i've got a question for ya." it was his standard haven't-fought-yet question because he wanted to see if he could get frisk back, maybe do one last reset and do it _right,_ not this kill-everything path. "do you think even the worst person can change...? that everybody can be a good person, if they just try?"

chara stepped forward, the knife glistening in the light of the hall.

"heh heh heh heh..." he chuckled. "all right. Well, here's a better question." he closed his sockets, and, when he opened them again, his eyelights were out, and his voice was a growl. _"do you wanna have a bad time?"_ )

 **(*RESET: YES/NO)**


End file.
